Analog-to-digital converters (ADCs) convert analog signals to digital signals. ADCs are typically powered by voltage supply rails. In certain types of ADCs, such as sigma-delta ADCs, the range of the analog input signal may be substantially smaller than the range of the supply voltage provided by the voltage supply rails. For instance, the analog input voltage may range from −500 mV to +500 mV, and the supply voltage may range from −3 V to +3 V.